Perforating gun



Ufli t 1 This invention relates to guns for firing projectiles, and moreparticularly to the type of gun employed for perforating the wall of aWell, such as a casing lining a Well bore, to establish fluidcommunication between the interior of the casing and the surroundingearth formations. Conventional bullet-firing perforating guns employrelatively intricate and expensive, mechanical, electrical, and gasorflame-employing firing systems for propelling the projectiles or bulletsto make the perforations. These are subject to numerous diflicultieswell-known to those familiar with this art, which it is a principalobject of this invention to overcome.

The most common arrangement employed in conventional gun perforatorscomprises a plurality of gun barrels, each of which carries a bullet anda charge of propellant explosive. The explosive charges for the severalbullets are set off from a common firing charge located in a firingchamber relatively remote from the individual barrels, the individualexplosive charges being fired by hot gases or flame propagated from thefiring chamber through passageways leading to the several bulletbarrels. Such an arrangement is subject to many sources of interferencewith the effective propagation of the gas or flame depended upon forfiring the individual bullet-propelling charges and result in frequentmis-firing or ineffective action by the bullets.

The present invention is directed to a new arrangement by which thedifiiculties occurring in the operation of more conventional bulletguns, as mentioned above, may be overcome by introducing between themain firing charge and an individual propellant charge, a hydraulicforce-transmitting medium. In this way the force of the main firingcharge is transmitted through the hydraulic transmitting medium in theform of a powerful compression wave, which is directed against theindividual charges of propellant explosive to set them off and propelthe bullets through the barrels. In this system, the hydraulicforce-transmitting medium may be likened to the firing pin of apercussion-fired gun or the like, and may be exemplified by the termhydraulic firing pin. The force transmitted through the hydraulic fluidto the propellant charges no doubt also supplements the force producedby the explosion of the charge and thus supplements the latter in itspropelling action upon the bullet.

It is a primary object, therefore, of this invention to provide aperforating gun of the general character described which employs ahydraulic fluid as a force-transmitting medium from the firing charge ofthe gun to the individual propellant charges for the several bullets orprojectiles fired from the gun.

The terms hydraulic fluid, hydraulic force-transmitting medium, and thelike, as used herein, contemplate substantially non-compressible fluids,such as water, oil, grease, materials of plastic character capable offlowing, and mixtures having these characteristics.

It is an important object of this invention to provide a Wellperforating gun having one or more barrels in which projectiles aresupported, each projectile being propelled States Pa Y 2 from its barrelby the explosion of a powder charge disposed in theprojectile-propelling relation thereto, the powder charge being set ofiby force transmitted from a common firing charge acting through asubstantially noncompressible substance of fluid character.

A further object is to provide a well perforating gun having one or morebarrels in which projectiles are supported and propelled by theexplosion of individual powder charges mounted in propelling relationthereto in the barrels, the individual charges being set off by forcetransmitted from a main firing charge through a confined passage inwhich is disposed a body of a hydraulic fluid, which acts to transmitthe force from the firing charge to the individual propellant charges tocause their ignition.

An additional object is to provide in a bullet firing gun of the generalcharacter described, a hydraulic forcetransmitting medium interposedbetween the main firing charge and the individual bullet propellantcharges and to further interpose between the hydraulic medium and themain firing charge an air space which may function as a shock absorberfor reaction or recoil from the hydraulic medium.

A further object of the invention is to provide a perforating gun inwhich the individual propellant charges for the projectiles are fired byforce transmitted through a hydraulic medium from a common firingcharge.

An additional object is to provide a well perforating gun having one ormore barrels in which projectiles are supported, each projectile beingpropelled from its barrel by the explosion of an individual explosivecharge, and having a firing chamber to receive a main firing charge, thefiring chamber being connected to the inner ends of each of the barrelsby a passageway, there being confined in said passageway a body of asubstantially non-compressible fluid for transmitting force from thefiring chamber to all of the individual propellant charges, at least aportion of said passage between the firing chamber and thenon-compressible fluid being left unfilled with fluid to provide anair-space therein.

Other and more specific objects and advantages of this invention willbecome more readily apparent from the following detailed descriptionwhen read in conjunction with the accompanying drawing, whichillustrates a useful embodiment in accordance with this invention.

In the drawing:

Fig.1 is a longitudinal sectional view of a gun embodying the presentinvention, the section being taken generally along line 1-1 of Fig. 2;

Fig. 2 is a cross-sectional view taken along line 2-2 of Fig. l; and

Fig. 3 is a cross-sectional view taken along line 3--3 of Fig. 1.

In the illustrative form of the invention, there is provided a body 10having a threaded pin 11 at its lower end adapted to receive cap orclosure 12 and having at its upper end an internally threadedcounterbore 13 to receive the threaded plug 15 of a firing head 16which, at its upper end, has a threaded counterbore 17 for connectionthereto of a conventional cable socket 18, from which the suspensionmeans for the gun, shown as a cable 19, extends upwardly.

Body 10 is provided with a plurality of longitudinally spaced, inwardlyextending, internally threaded recesses 20, for receiving externallythreaded gun barrels 21, alternate ones of which may face in oppositedirections, as shown, but which, it will be understood, may face in onedirection, if desired. Each of the gun barrels has a bore 22 forreceiving a bullet .or projectile 23, which is secured to a shear disk24 which bears against the inner end of the barrel and forms a closurebetween the inner end of the barrel, and a chamber 25 which forms aninward extension of recess 21 and is adapted to receive the propellantexplosive charge 26, which may be of any conventional character. It willbe understood that the gun barrel arrangement and the form of theprojectile, the shear disk, and the projectile charges may be of anyknown and generally conventional construction and arrangement, the.present invention not being limited to the details of these elements.

v A passage 28 .of restricted cross-sectional area leads downwardly fromthe bottom of counterbore 13 through body to one side of thelongitudinal axis of the body, and lateral passages 29 connect passage28 to propellant chambers 25, as illustrated. In the illustrativeexample two of the passages 28 are employed, each comrnunicating withone set of the gun barrels-facing in one direction. While a singlepassage may be employed to connect to all of the propellant chambers, itis generally simpler, mechanically, to provide a separate passage foreach set of oppositely facing gun barrels, although if all of the gunbarrels face in the same direction, a single passage 28 will besufficient to connect to all of the propellant chambers of such barrels.

The lower ends of passages 28 are closed, in any suitable manner, asillustrated, by means of the abutting end face 30 of closure cap 12,suitable seals 31 being provided between the end of body 10 and cap 30to assure a fluid-tight seal between these members.

A fluid 3-2 is contained in passages 28, the fluid 32 having theproperties previously mentioned, namely, a substantiallynon-compressible material of flowable character. In most instances it ispreferable that the fluid 32 should not fill passages 28 completely, butthat a section, designated 28a, in the upper portions of passages 28should be left unfilled with the hydraulic fluid. Sections 28a will, ofcourse, contain atmospheric air. The sections 28a perform an importantshock-absorbing function, as will be described more fully hereinafter.The body of fluid 32 will preferably be in direct contact with thepropellant charges 26.

The threaded plug 15 of a firing head 16 has a bore or recess 35, whichdefines a firing chamber which is adapted to receive a charge of powder36, which constitutes a main firing charge, or so-called primer, for thegun. At its inner end, recess 35 is counterbored and internally threadedto receive a choke bushing 37 which communicates at one end with firingchamber 35 and at the other end with a reduced diameter bore 33, inwhich is seated a conventional explosive ignition cap 40 adapted to beelectrically fired in the conventional manner by current providedthrough a conductor 41, which extends through cable 19 to the surface inaccordance with conventional practices for electrically firing fuses orinitiating charges in guns of the general character herein described.

In operation of the gun, the parts may be assembled, as in the drawing,with the projectiles 23 in the respective barrel bores 22, and with abody of suitable hydraulic fluid 32, which preferably is water,contained in passages 28 filling the same to a point below or spacedfrom the upper ends of the passages which communicate with firingchamber 35, the upper sections 28a of the passages 28, above the levelof fluid 32 therein, being filled with air. 1e propellant charges 26,firing charge 36, and initiating charge 40 will, of course, be properlyinstalled and the parts otherwise suitably assembled and arranged. Thenthe gun is lowered into the well by means of cable 19 to a point in thewell at which the perforations are to be made, whereupon the initiatingcharge 40 may be fired and this, in turn, will set off the main firingcharge or primer 36. The explosion of the latter will be transmittedthrough passages 28 to the body of fluid 32 and the forceof thatexplosion will be transmitted by the hydraulic fluid to the individualpropellant charges 26, which will be set off by the impact-ive orcompressiveforces thus exerted thereon by the hy- .draulic fluid, andwill drive bullets-23 from barrels 22,

the force of the propellant explosive being built up by resistance ofshear disk 24, in the well-known manner, to increase the propellingforce applied to the bullets.

Since fluid 32 is substantially non-compressible, it will be understoodthat the force transmitted thereby will be exerted in all directions;hence, it is found in most cases that some relief for forces directedagainst the surrounding portions of the gun body is desirable and tothis end it is usually preferable to provide some type of shockabsorbing medium which will afford such relief. An effective shockabsorbing arrangement for this purpose is that provided by leaving anair space between the column of fluid 32 and firing chamber 35, thisspace being filled with air, Will act to absorb recoil forces andprevent shattering of the gun body by the forces applied to fluid 32 bythe explosion of the priming charge 36 and propellant charges 26.

By the arrangement described, the force of the explosion from charge 36will be transmitted substantially simultaneously by means of fluid 32 toall of the several propellant charges 26, so that all of the bulletsfire simultaneously and with maximum efliciency.

It will be understood that various changes and modifications may be madein the details of the illustrative embodiment within the scope of theappended claims, but without departing from the spirit of thisinvention.

What I claim and desire to secure by Letters Patent is:

1. A perforating gun comprising a gun barrel having a projectiletherein, a firing chamber spaced from the gun barrel to receive a firingcharge, a passage connecting the firing chamber to the gun barrel, anexplosive propellant charge in the gun barrel disposed in propellingrelation to the projectile therein, and a body of a substantiallynon-compressible material of hydraulic force transmitting characterconfined in said passage and in contact with said propellant charge,said non-compressible material 'being operable upon ignition of a firingcharge in said firing chamber to hydraulically transmit the forcethereof to the propellant charge, whereby to set-off the propellantcharge and to increase the propelling force on said projectile.

2. A perforating gun comprising a gun barrel having a projectiletherein, a firing chamber spaced from the gun barrel to receive a firingcharge, a passage connecting the firing chamber to the gun barrel, anexplosive propellant charge in the gun barrel disposed in propellingrelation to the projectile therein, and a body of a substantiallynon-compressible material of hydraulic forcetransmitting characterconfined in said passage and in contact with said propellant charge,said passage having an air space between said firing chamber and saidbody of material, said non-compressible material being operable uponignition of a firing charge in said firing chamber to hydraulicallytransmit the force thereof to the propellant charge, whereby to set-offthe propellant charge and to increase the propelling force on saidprojectile.

3. A perforating gun comprising a gun barrel having a projectiletherein, a firing chamber spaced from the gun barrel to receive a firingcharge, a passage connecting the firing chamber to the gun barrel, anexplosive propellant charge in the gun barrel disposed in propellingrelation to the projectile therein, and a body of water confined in saidpassage and in contact with said propellant charge, said body of waterbeing operable upon ignition of a firing charge in said firing chamberto hydraulically transmit the force thereof to the propellant charge,whereby to set-off the propellant charge and to increase the propellingforce on said projectile.

4. A perforating gun comprising a gun barrel having a projectiletherein, a firing chamber spaced from the gun barrel to receive a firingcharge, a passage connecting the firing chamber to the gun barrel, anexplosive propellant charge in the gun barrel disposed in propellingrelation to the projectile therein, a body of water confined in saidpassageand in contact with said propellant charge,

and an air space in said passage between said firing chamber and saidbody of Water, said body of water being operable upon ignition of afiring charge in said firing chamber to hydraulically transmit the forcethereof to the propellant charge, whereby to set-off the propellantcharge and to increase the propelling force on said a projectile.

5. A perforating gun comprising a plurality of spaced apart gun barrelseach having a projectile therein, a firing chamber spaced from theseveral gun barrels to receive a firing charge, passage means connectingthe firing chamber to the several gun barrels, an explosive propellantcharge in each of the gun barrels disposed in propelling relation to theprojectile therein, and a continuous body of a substantiallynon-compressible material of flowable character confined in said passagemeans and in contact with each of said propellant charges, saidnon-compressible material'being operable upon ignition of a firingcharge in said firing chamber to hydraulically transmit the forcethereof to the propellant charges, whereby to set off the propellantcharges and to increase the propelling forces on said projectiles.

6. The improvement in a perforating gun as defined in claim 5 whereinsaid substantially non-compressible material is water.

l 7. A perforating gun comprising a plurality of spaced apart gunbarrels each having a projectile therein, a firing chamber spaced fromthe several gun barrels to receive a firing charge, passage meansconnecting the firing chamber to the several gun barrels, an explosivepropellant charge in each of the gun barrels disposed in propellingrelation to the propectile therein, and a continuous body of asubstantially non-compressible material of flowable character confinedin said passage and'in contact with each of said propellant charges, thevolume of said material being less than that of'said passage to therebydefine an air-filled space portion in said passage between said chamberand said body of non-compressible material.

'8. A perforating gun comprising a plurality of spaced apart gun barrelseach having a proj chamber spaced from the several gun barrels toreceive a firing charge, passage means connecting the firing chamber tothe several gun barrels, an explosive propellant charge in each of thegun barrels disposed in propelling ectile therein, a firing I relationto the projectile therein, and a continuous body of water confined insaid passage means and in contact with each of said propellant charges.

9. A perforating gun comprising a plurality of spaced apart gun barrelseach having a projectile therein, a firing chamber spaced from theseveral gun barrels to receive a firing charge, passage means connectingthe firing chamber to the several gun barrels, an explosive propellantcharge in each of the gun barrels disposed in propelling relation to theprojectile therein, a continuous body of a substantiallynon-compressible material of fiowable character confined in said passageand in contact with each of said propellant charges, and shockabsorbingmeans comprising an air-filled space in said passage between said firingchamber and said body of non-compressible material.

10. A perforating gun, comprising, a body having a plurality of spacedapart inwardly extending gun barrels each having a projectile therein, afiring chamber spaced from the inner ends of the several gun barrels toreceive a firing charge, restricted diameter passage means connectingthe firing chamber to the inner ends of the several gun barrels, anexplosive propellant charge in the inner end of each of the gun barrelsdisposed in propelling relation to the projectile therein, and acontinuous body of a substantially non-compressible material of tlowablecharacter confined in said passage and in contact with each of saidpropellant charges, said noncompressible material being operable uponignition of a firing charge in said firing chamber to hydraulicallytransmit the force thereof to the propellant charges, whereby to set ofithe propellant charges and to increase the propelling forces on saidprojectiles.

11. A perforating gun as defined by claim 10 wherein said substantiallynon-compressible material is water.

References Cited in the file of this patent UNITED STATES PATENTS2,265,982 Bolton Dec. 16, 1941 2,414,900 Schiavon Jan. 28, 19472,456,977 McCullough Dec. 21, 1948 2,457,277 Schlumberger Dec. 28, 19482,726,602 Davis et Dec. 13, 19

